End expander for structural toy rods



y 1933. F. SCHROEDER 1,920,021

END EXPANDER FOR STRUCTURAL TOY RODS Filed Jan. 28, 1935 l 'atented July 25, 1933 j UNITED. STATES PATENT- oFFlcE. I

FRANK scnnonnnn; on KANSAS CITY, MIssoUnI, AssIeNon TO THE 'roY TINKERS INC., EVANSTON, ILLINOIS, A CORPORATION or ILLINOIS END EXIE'ANDER FOR STRUCTURALTOY RODS Application filed; January 2s, 1933. ser al mycsaom.

My invention relates to the class of toy construction blocks which include wooden rods of uniform diameter and varying lengths, together with connecting members provided with cylindrical bores of uniformdiameter in which the ends of such rods can be firmly socketed by a mere slidable insertion of these rod ends into such bores.

To secure an adequately tight socketing of the rods in the connecting members while also facilitating the attaching of the rods to such connecting elements it has long been customary to provide each end of such a rod with a diametric longitudinal slot, usually of greater length than the depth of the bores. This causes each rod end presents two spaced prongs or tines which can flex toward each other'to facilitate their insertion in a bore of a connecting member, and

sothat the two prongs of each rod end will thereafter be sprung apart by the resiliency of the wood for firmengagement with opposite wall portions, of the bore into which a slotted end of a rod is inserted,

This slotted end construction of the'rod also has the important advantage that when the prongs are flexed toward each other at the beginning of the insertion of the rod end in a bore of a connecting Inember, the

rod can extend somewhat at an'angle tothe axis of the bore, thereby permitting the erection of structures or mechanism-simulations in which pairs of rods ext nd. at acute angles ,(such as angles of degrees) toeach other when socketed in adjacent bores inthe sameconnecting member.

In practice, the strains imposed on such slotted rod ends by an oft repeated to-and' fro flexing of their prongs causes a gradual. deterioration of the resiliency of the rod ends, particularly when thisfle'xin'g has; to

be carried to the extent required when connecting adjacent rods inacute-angled rela tion to each other. -Qonsequ'ently," a prolonged use of such toy construction elements, and even a fairly short period with arough handling of the rods, will leave someof the rod ends with a permanent set in which the two prongs slope toward each other 'and present a tapering end no longer adapted for being firmly gripped by the bore wall which would tightly fit that rod end before such a: reduction in its resiliency.

'Mypresent invention aims to provide a simple and inexpensive auxiliary member which can readily be inserted (even by a fairly young child in a longitudinally slotted rod-end for affording a prong-separating resiliency fully equal to the natural resiliency of the wood innew rods, thereby per mitting-a continued and elfective use of such rods. Illustrative of my solution of this problem,

Fig. 1 is an enlarged section (atright angles to its axis) through a connecting disk provided with'r'adial bores for receiving rod ends, with full lines also showing both a portion of a horizontal end which has lost its resiliency, and a portion of a vertical rod having its end prongs spread apart by ,an interposed spreader spring embodying my lnvention.

Fig. 2 is a still more enlarged perspective view of'this prong-spreading spring before its insertion into the slot of a rod end.

Fig. 3*is an elevation of a portion of a rod in which the prongs have lost their resiliency, showing the spreader spring during the initial period of its insertion.

Fig. 4 is an elevation similar to" Fig. '3, showing'the end prongs of. the rod as spreadapart when the spring has been completely inserted. i I i Fig.5 is -aplan view taken from the line 55 of Fig. 4, and Fig. 6 a section taken along the line 6-6 of Fig. 4.

Fig. 7 is an enlarged side elevation of the same spreader spring as initially formed, with dotted lines showing a side elevation of a split rod end ofthe corresponding size when this rod end still has its natural resil-j iency. I

Fig. 8 is aview similarto Fig. 4:, showing an alternative shaping of my resilient prongdepth extending into it, and also shows portions ofw'ooden rods designed for connection by such a disk. Each of these rods has a diametric slot 3 extending into its end portion for a somewhat greater length than the uniform depth of the said bores, this being a saw slot presenting parallel walls. With the rod ends of the same diameter as the bores 2, this rod can easily be slid axially intoanyone of the bores for part, or all of the length of the bore, after which the resiliency of the wood cooperateswith the frictional engaging of the .two rod-end prongs by the wall of the bore to hold the rod firmly anchored to. the disk.

With new rods, or rods which have not had their slotted end portions subjected many times to end-compressing strains, the resiliency of the wood isample for holding the two end prongs P against opposite sides of the wall of the bore 2 in which the rod end is inserted. And if the attaching and detaching of the rods was alwaysefiectedby a purely axial movement of the rod with re spect rto the corresponding bore, such rods when made of the commonly available dowel stock will retaintheir resiliencyfor many.

years. v

However, if two rods R and B have previously been connected by other, elements of the structural toy setso that they converge at an angle of todegrees toward each other, the prongs of the adjacent free ends of these rods must be flexed toward each other-(as shown in dotted lines in Fig. l) to permit these rod ends to beslid into the corre sponding. bores.-- This compressing of the slottedrodjends, which also must be re 'peated'when disassembling the connecting disk from the rods, imposesa considerable strain on the rod end portions and intime practically annuls the resiliency; so. that the detached rod has its prongs converging toward the tip of the rod as shown for thejrod 5 in Fig. .1, or even to the increased extent of having the two prongs. bear agalnst each 7 other at their tip V Consequently, the 1 weakened rod 5 presents a non-res1l1ent end tapering toward its tip, and when this rod is inserted-into a bore (asshown for the rod 5 in Fig. 1), the rod end contacts with the wall of the bore only.

stores the initial resiliency'to the slotted rod end.

along a circular-line, so that thejrod can rock about the axis 'of the bore and also can easily slip out of the bore. Tomake a rod with such resilientless slotted ends still u s able, I provide prong spreaders,,each formed of a resilient metal strip considerably thinner than the width WV of the rod-end slot 3 in the rod (as initially manufactured), of less width than the diameter of the rod, and bent flatwise to present a sinuous edge.

In the preferred type shown in Figs. 2 t0 7 inclusive, the resilient prong spreader S is formed from a steel strip, desirably of a thickness not exceeding about one-fourth the width W of the rod-end slot 8. This strip is CUIVBClflZltWlSB so as to present two end portions 8 and 9 convexed in the same direction and connected by a medial portion lOwhichis convexed in the opposite direction, as shown in Fig. 2.

Moreover, this curving is such that the maximum distance D to which the central portion arches away. from a plane P (Fig. 7 tangential to the outward faces of the two end portions8 and 9is materially greater than said rod-end slot width W, while the maximum spacing H of each strip end from the same plane P preferably is less than the said slot width. In practice, I desirably this manner, themedial portion of the spreader is reduced in the extent of, its bow-.

ingbecause of the previously recited'difi'erence between the distances D and Vi in Fig. 7.; but both tips of the spreader may still be freely spaced from the slot wall (as shown in Figs. land '7) along which the medial bowed portion 10' slides, so that these tips will not scrape on .the. last named slot wall to interfere with the easy inserting of such spreader even by'a young child. 1

" hen once pushed into a rod-end slot in thismanner, the resiliency of my spreader causes it to spreadthe prongs back to their normal spacing, as shown in Fig.) The inserted spreader then exerts sufficient pressure against the opposed walls of the slot to prevent having the spreader shaken out, and also yields sufliciently to permit the prongs to be approached to each other when the rod end needs to he slid into a; connector bore with theaxisof the rod somewhat at an an .gleto that of the bore In other words, my

simple and cheap spreader effectively refourths as wide as the diameterof the rod part of the rods of a structural toy set of this class may lose their resiliencyin ordinary use, the including of a supply of such resiliency-restoring prong spreaders adds only trivially to the cost of the set, although greatly increasing the period of time during which the elements of the set will give con tinuous satisfaction to its users.

However, while I have heretofore described my prong spreader as having three successive portions curved in alternately opposite directions, I do not wish to be limited as to this or other here disclosed details, since changes might be made Without departing either from the spirit of my invention or from the appended claims. For example, Figs. 8 and 9 show a spreader 12 of a simple S-shaped edge view.

I claim as my invention: o

1. In a toy construction set including a rod which has its end portion divided into two prongs by a diametric slot, means to resiliently hold said prongs apart comprising a spring slidably insertible into the slot and made from flat resilient metal of a thickness less than half the distance between the opposed walls of the slot; the spring being formed to a sinuous side elevation to present convexed face portions alternately to the said opposed walls.

2. In a toy construction set including a rod which has its end portion divided into two prongs by a diametric slot, means to resiliently hold said prongs apart comprising a spring slidably insertible into the slot and made from flat resilient metal of a thickness less than half the distance between the opposed walls of the slot; the spring being formed to a sinous side elevation to present convexed face portions alternately to the said opposed walls; and the spring before its insertion having a spread transversely of the general plane of the spring, greater. than the width of the said slot.

3. In a .toy construction set including a rod which has its end portion divided into two prongs by a diametric slot, means to resiliently hold said prongs apart comprising a spring slidably insertible-into the slot and made from flat resilient metal of a thickness less than half the distance between the opposed walls of the slot the spring being formed to a sinuous side elevation to present two face portions bowed away from the general medial plane of the spring and an. interposed face portion bowed in the opposite direction.

4. In a toy construction set including a rod which has its end portion divided into two prongs by a diametric slot, means to resiliently hold said prongs apart comprising a spring slidably insertible into the slot and made from, fiat resilient metal or a thickness less than half the distance between the opposed walls of the slot; the spring being formed to a sinuous side elevation to two prongs by a diametric slot, means to resiliently hold said prongsapart comprising a spring as per claim 4, in which each tip of the spring is spaced from the said plane by a distance less than the said maximum spacing.

' FRANK SCHROEDER. 

